We all know what happens to most stars in the final stages of their lives: they explode violently in an event called a supernova, when they run out of “fuel” and collapse themselves. This led to some of the most powerful explosions in the universe, marking the end of life for a star. So when astronomers used NASA’s Hubble Space Telescope to observe a “dying” star, they thought they would see the same predictable events. What they see is a supernova, but the star that created it looks different from the others.
When a giant star is “dead”, it is (almost) always wrapped in a layer of hydrogen. The researchers point out that this layer of hydrogen often hides the incredibly high-temperature interior of the star, which, in our eyes, is blue. When a star becomes a supernova, hydrogen and everything else that makes up the star are excreted in an explosion. However, the star that created the supernova event known as 2019yvr did not appear to have any hydrogen in the years leading up to its explosion. This does not fit the existing model of the star, forcing scientists to come up with another explanation.
“We haven’t seen anything like this before,” Charles Kilpatrick, lead author of the study, said in a statement. “If a star explodes without hydrogen, it should be extremely blue — very, very hot. If a star’s outer layer were free of hydrogen, it would almost impossible for it to be so hot. We studied every model that could explain such a star, and each model needed the star to have hydrogen, and from its supernova, we knew it wasn’t. It extends the physical possibility. ”
After discovering the exploding star, astronomers looked back at Hubble’s catalog and found images of it in the years before it exploded. They also looked at the material the star was blasted into space and noticed that its mass appeared to interact with a hydrogen cloud not far from where the star died. This led the researchers to come up with a theory that might explain what they saw.
“Astronomers suspect that in the years leading up to we saw supernovae, stars experienced violent eruptions or death pains,” Kilpatrick explained. “The discovery of this star provides some of the most direct evidence yet that the star experienced a catastrophic explosion that caused them to lose mass before the explosion. If the star were to make these eruptions, it would probably have discharged its hydrogen decades before the explosion. ”
So if the star blows up its hydrogen layer before it collapses into a supernova, this could explain the apparent lack of hydrogen in the debris left behind by the star. Or, in another new theory, the star may have a companion star that peels off the hydrogen layer of its outer layer before the supernova explodes. Both cases could explain the resulting observations, but it could take a decade or more before researchers can gather enough data to confirm or refute their theories.
